It is desirable to use thermoplastic compounds such as polyethylene terephthalate or polyphenylene sulfide for injection or casting onto thermoset components, especially semiconductor components, which have been provided with a housing made from a thermoset material. This is the case, for example, when a semiconductor component is to be provided with a mount made from a thermoplastic material, in order to make the component installable.
In this context, or generally when joining or combining thermoset materials to or with thermoplastic materials, the problem exists of providing effective adhesion between the two different materials. One possibility is to deform the surface of the thermoset in order to create greater adhesion between a thermoset part and a thermoplastic part which is to be applied to it. This is not possible, however, for housings of semiconductor components.
It is also not possible to employ, for example, the option of two-component injection molding, a method by means of which thermoset/thermoplastic composites can be created, since this involves the subsequent attachment of components to the semiconductor component when its processing is already complete.
Thus, when a thermoplastic material is applied subsequently to a thermoset material by conventional methods, the problem generally exists that the adhesion which develops by fusion of the components at their interfaces (interdiffusion of the molecule chains) on contact of the heated thermoplastic material or thermoplastic melt on the cold thermoset material is inadequate and that, as a result, delamination often occurs.